The long-term objective is to understand the neural organization of the masticatory system and the impact of dental maladies on that organization. Within that framework, we have chosen for study the masseteric silent period. The silent period has been defined as an absolute or relative decrease of electrical activity in the midst of an otherwise sustained contraction. The specific aims are: (1) to determine the contribution of various afferent fiber systems to the silent period evoked by a tap to the chin, (2) to investigate the influence of clinical maladies and dental interventions on the silent period, and (3) to determine the feasibility of using additional electrodiagnostic techniques for assessing the masticatory system. The methods will include measuring masseteric silent periods recorded by surface electrodes in response to chin taps, tooth taps, and cutaneous stimulation. The results of the proposed experiments will provide precise measurements of the parameters of the reflexes of the masticatory system. From these measurements we shall be able to make deductions about the organization of the central mechanisms controlling the jaw muscles and how these are altered by dental maladies.